A liquid crystal panel used in a liquid crystal display device, such as a liquid crystal television set, does not emit light by itself. Thus, the liquid crystal panel uses a backlight unit as a separate lighting device. This backlight unit is installed on a back side (on a side opposite to the display surface) of the liquid crystal panel and includes: a chassis having an opening on the liquid crystal panel side; a light source housed in the chassis; a reflection sheet disposed along an inner surface of the chassis and reflecting light toward the opening side of the chassis; and an optical member (such as a diffuser sheet) disposed at the opening of the chassis for causing the light emitted from the light source to be efficiently output toward the liquid crystal panel side.
In the backlight unit of the above configuration, LEDs may be used as the light source for saving power consumption. For example, a number of LEDs are disposed two-dimensionally on a bottom plate of the chassis. However, there has been the problem that, when the output light from the backlight unit is observed from a front side, dark areas are generated at the four corner portions of the screen due to insufficient light amount. In order to solve this problem, a technology is proposed in Patent Document 1 described below.
Patent Document 1: Japanese Unexamined Patent Publication No. 2006-120644